镧
氢
人工神经网络
超导电性
材料科学
氮气
物理
凝聚态物理
计算机科学
人工智能
核物理学
量子力学
作者
Takahiro Ishikawa,Yuta Tanaka,Shinji Tsuneyuki
出处
期刊:Physical review
[American Physical Society]
日期:2024-03-14
卷期号:109 (9)
被引量:3
标识
DOI:10.1103/physrevb.109.094106
摘要
Recently, Grockowiak et al. reported ``hot superconductivity'' in ternary or multinary compounds based on lanthanum hydride [A. D. Grockowiak et al., Front. Electron. Mater. 2, 837651 (2022)]. In this paper, we explored thermodynamically stable phases and superconducting phases in the lanthanum-nitrogen-hydrogen system (${\mathrm{La}}_{x}{\mathrm{N}}_{y}{\mathrm{H}}_{1\ensuremath{-}x\ensuremath{-}y}, 0\ensuremath{\le}x\ensuremath{\le}1, 0\ensuremath{\le}y\ensuremath{\le}1$) at a pressure of 20 GPa. We rapidly and accurately constructed the formation-enthalpy convex hull using an evolutionary construction scheme based on density functional theory calculations, extracting the candidates for stable and moderately metastable compounds by the universal neural network potential calculations. The convex hull diagram shows that more than 50 compounds emerge as stable and moderately metastable phases in the region of $\mathrm{\ensuremath{\Delta}}H\ensuremath{\le}4.4$ mRy/atom. In particular, the compounds are concentrated on the line of $x=0.5$ connecting between LaH and LaN. We found that the superconductivity is gradually enhanced due to N doping for LaH and the superconducting critical temperature ${T}_{\mathrm{c}}$ reaches 8.77 K in ${\mathrm{La}}_{2}\mathrm{NH}$ with $y=0.25$. In addition, we predicted that metastable ${\mathrm{La}}_{2}{\mathrm{NH}}_{2}$ shows the highest ${T}_{\mathrm{c}}$ value, 14.41 K, of all the ternary compounds predicted in this study. These results suggest that it is difficult to obtain the hot superconductivity in the La-H compounds with N at 20 GPa.
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